The present invention relates to document image processing and more particularly to duplex document handling.
Duplex copying is an important feature of copier systems operating in businesses. Although, computer storage of document images holds great promise for the future, paper is still the predominant mode of document storage as evidence by rising consumption of paper. A 50% reduction in paper usage is achieved by the use of two-sided documents.
Problems exist however in the handling of two-sided documents in copying and in other office operations such as scanning and faxing. Each page must pass by the scanning system twice, greatly increasing the complexity of the feeder mechanism. Difficulties arise in synchronizing the front page and back page order. When a document containing an odd number of pages are copied onto both front and back sides, often the front page of the document is left as a single sided copy rather than the last page. The same problems may potentially arise in faxing and scanning.
One known solution is described in Japanese Patent No. 7283906 which teaches the use of twin scanner systems including separate CCD sensors so that both the front and the back of a page are scanned in the same pass. This approach requires duplication of not only the CCD sensors but also other scanning hardware and is thus very expensive to implement.
What is needed is an improved economical system and method for handling two-sided documents when copying, scanning, or faxing.